Method of producing active form coke

ABSTRACT

Active form coke is made from coal by passing the coal granulate downwardly through a preheating and pyrolysis zone, a heating zone, an aftertreatment zone and a cooling zone by moving respective grate bars of grates in each zone so that a bed of granules on one grate trickles uniformly onto the next lower grate. In the preheating, heating and aftertreatment zone CO 2  or steam are passed through the beds by laterally introducing the gas at one side and withdrawing the gas on the opposite side of a respective bed.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national phase application of PCT/EP 85/00113filed 16 Mar. 1985 and based, in turn, upon a German nationalapplication No. P 34 10 893.9 filed 24 Mar. 1984 under the InternationalConvention.

FIELD OF THE INVENTION

The invention relates to a process and an apparatus for the manufactureof activated coke in the form of a granulate based on pretreated blackcoal in which premolded granulates are passed through differenttreatment zones of a shaft and in the zones are pyrolyzed by means oflaterally introduced and withdrawn gases or vapors, heated, activatedwith steam or CO₂ gas or a mixture of steam or CO₂ gas and post-treatedand cooled.

BACKGROUND OF THE INVENTION

It is known to manufacture activated form coke from pretreated blackcoal material in the form of a granulate or a particulate product, theblack coal being powdered and made into a paste with a binder andtransformed into granulates which are subsequently pyrolyzed andactivated, thereby yielding a corresponding particulate or granulatedproduct.

When pretreating the black coal it is possible in addition to precedethe powdering by a de-ashing or extraction or oxidation step.

Known binders for converting the powdered black coal into a pasteinclude, black coal tar and wood tar, inorganic gels such as silica geland iron or aluminum hydroxide, optionally in combination withneutralizing substances such as caustic soda or lime.

It is also known for the manufacture of activated coke to convey thepretreated products intended for that purpose through a shaft whichcomprises the aforementioned various treatment zones, in which thepyrolysis, heating and activating takes place by laterally introducedand discharged gases or vapors.

In the known process, the material to be treated and which is conveyedthrough the shaft is rerouted repeatedly in opposite directions in theform of a column of material for the attainment of increased reactionareas and an effective mixing of the reagents, the gases or vapourspassing therethrough in a direction transversely to the columns.

In another embodiment the material to be treated is passed throughsleeve-shaped internal structures overlapping each other and centrallypassing through the shaft from the top downwards and the material columnis subjected to a flow therethrough of the treatment gases which areintroduced sideways.

The known processes for attaining the required thermal and materialexchange require relatively long residence periods the individual zones,in particularly if the flow through the column of material proceedsvertically whereby the energy consumption for effecting the flow and fortransferring the heat is increased.

Moreover, an uneven treatment of the material particles contained in thematerial column results from the pronounced flow profile.

Finally, substantial abrasion losses take place even during themanufacture of the activated coke, because the material particles in thelower region of the material column are subjected to the static pressureof the material load and accordingly high frictional forces in relationto adjoining material particles or the internal structures in the shaftare unavoidable.

SUMMARY OF THE INVENTION

In accordance with the present invention granulates of uniformdimensions having longitudinal and transverse dimensions or a diameterof 6 to 25 mm are molded and are provided in plane shallow beds adaptedto the shaft cross section and of uniform bed thickness across the crosssection.

Each bed is supported in the shaft by grids at different levels oneabove the other, leaving free interspaces, and after predeterminedresidence periods in the individual stages are conveyed through theshaft from the top to the bottom, starting with the lowermost bed,through the discharge means thereof, the beds during the periods ofresistance on the grids in the treatment zones being subjected to a flowtherethrough of the gases or vapours.

The gases or vapors are introduced into the free interspaces betweenadjoining beds and are discharged from other interspaces on the oppositeside of the bed from that in which they were introduced.

The flow through each bed is normal to the plane of the bed, and thebeds after the respective periods of residence on the individual gridsare disrupted by removal of at least some the grid rods being removed atcontrolled times from the plane of the grid, the granulates therebybeing transferred in the form of a uniform free flow onto the respectivenext lower grid in such a manner that once again beds are formed havinguniform bed thicknesses across their entire cross sections.

Due to the use of granulates of uniform sizes approximately uniforminterstitial voids are formed in the individual beds, a factor ofparticular importance in the context of the flow of the gases or vaporsthrough the beds in the individual treatment zones.

In combination with the shallow beds having uniform bed thicknesses overtheir entire cross section there is over the entire cross sectional areaof the beds, an approximately uniform flow resistance such that when thebeds are exposed to a uniform input flow, there will be a uniform flowthrough the beds.

The uniform input flow to the individual beds in the region where thegases or vapors are introduced into the shaft is attained by feeding thegases or vapors into the free interspaces between the respectiveadjoining beds.

If the gases or vapors flow through several beds one above the other,any uneveness of the flow, e.g. locally differing flow velocities orlocal differences in pressure of the gases or vapors emerging from thepreceding bed will be compensated for in such a manner that suchirregularities cannot adversely affect the entire flow path of thegases, until they are discharged.

In view of the uniform treatment of all granulates and in view of theintensive flow through the interstices and simultaneous turbulence ofthe gases in the interstices, the surfaces of the granules are exposedrepeatedly to fresh gas molecules so that a very intensive thermal andmaterial exchange is attained, resulting in a substantial decrease inthe reaction period.

The subdivision of the material composed of the granulate to be treatedinto shallow and plane beds spaced apart from one another moreoverensures that the granules at no stage of their treatment will besubjected to excessive static pressure which might result in theundesirable abrasion effects.

However, it is important that the beds on their way through thetreatment zones maintain a uniform bed thickness. By the controlledwithdrawal of at least some of the grid rods from the respective gridplane the bed maintained on the grid rods is caused to break up, thecontrolled movement of the grid rods serving to attain the desireduniform trickle flow and the formation on the next following grid of abed once again having a bed thickness which is uniform over the crosssection.

Appropriate preliminary trickle experiments may serve to determine as afunction of the shape and size of the material particles the mostadvantageous pattern of movement of the grid rods, whereafter thecontrol of the movement of the grid rods may be adjusted accordingly.The movement of the grid rods simultaneously brings about a breaking upof any bridge formations which may have arisen in the granulate. In thiscontext provision may be made for a controlled lowering or raising ofthe movable grid rods as a function of time.

It is advantageous for the bed during the period of residence in thepyrolysis zone to be permeated by the pyrolysis gas in countercurrent.Accordingly the pyrolysis gas is passed through the bed in a directionopposite the direction of transport of the granulate from one grid tothe next. The pyrolysis zone in this context may include a plurality ofbeds through which the pyrolysis gas passes successively. The pyrolysisgas generally has a temperature of about 400° C.

The countercurrent flow of the pyrolysis gas through the beds makes itpossible to attain or slightly exceed a loosening threshold of thegranulates in the bed by appropriate adjustment of the flow velocity ofthe gases, such that sintering together or cohesion of the granulates inthe pyrolysis zone can be avoided substantially by an appropriateadjustment of the flow velocity of the pyrolysis gas. The flow velocitymay amount up to 5 m/sec based on the free cross section of the shaft.

It is particularly advantageous for the beds during their periods ofresidence in the pyrolysis zone to be locally shielded partially andalternatingly against the passage therethrough of the pyrolysis gaseswhich pass through the respective remaining regions until the looseningthreshold is attained or exceeded. In this manner an alternating partialmovement of the granulates in the bed or even a partial repacking fromthe regions through which the gas happens to flow into those regionsthrough which no flow takes place may be attained, the local changeoverof partial flow patterns repeatedly serving to attain a return to aloosened state of the previously repacked granulates.

During the treatment of the granulates it is advantageous for the flowthrough the beds in the heating, activation and post-treatment zoneduring one or more periods of residence to take place in one directionand during other periods of residence in the opposite direction so thatthe thermal gradient in the beds is reduced.

It is of particular advantage in accordance with a further developmentof the inventive concept for the beds in the cooling zone to be sprayedwith water and the steam generated in the cooling zone to be passed tothe bed of at least one of the preceding treatment zones. As a result,in addition to the cooling effect, a substantial part of the steamrequired for the preceding treatment of the granulates is obtainedthereby resulting in a substantial saving of energy.

Apparatus for carrying out the process described in the aforegoing areof a type comprising a shaft having internal structures and serving foraccommodating a granulate to be conveyed through the shaft, connected tomeans for feeding and discharging the gases and/or vapors and providedwith lateral inlet and outlet apertures for such gases.

According to the invention the interior of the shaft is subdivided bygrids into chambers and in the upper portion of the shaft a means forfeeding preporportioned beds of granulates which each fill the chambersonly partly and for uniformly distributing the granulates over the shaftcross section on the uppermost grid are provided. The grids are composedat least in part of movable grid rods having operating means andcontrollable drive means associated therewith for the temporary andperiodically controlled increasing of the free spaces between adjoininggrid rods by the withdrawal of part of the grid rods from the gridplane.

In this context it is advantageous if the apparatus for the feeding anduniform distribution of the premeasured amount of bed material comprisesa slider box adapted to be moved in an inlet lock across the shaft crosssection, its bottom being formed by a grid the construction of whichcorresponds to the grids in the shaft and being operable in the samemanner.

It is furthermore advantageous if at least between adjoining grids ofdifferent treatment zones there is provided a partition formed bypivotal louver slats, adapted to be moved into the closed and openposition respectively by adjustment of the slats. Such partitions mayalso in addition be provided in the region where the bed enters theshaft and where it leaves the shaft. Such partitions make possible, in aparticularly simple manner, an aerodynamic separation of the treatmentgases being passed in the individual zones through the beds and havingdifferent compositions and also different temperatures.

In order to facilitate the above described partial flow through the bedsin the pyrolysis zone, it is advantageous that immediately underneaththe grid in the pyrolysis zone of the shaft there is in each caseprovided a grid-shaped insert for the formation of parallel flowpassages. Flaps pivotal about horizontal axes are provided in the flowpassages which in a pattern like the squares of a chessboard are adaptedto be pivoted alternatingly in group in the plane of the shaft or normalthereto. A simple design of the pivotal flaps has for each row of flapstwo horizontal axes, one above the other, for the alternate arrangementand group-wise pivoting of the flaps.

Further preferred details concerning the particular design of the gridsincluding their movable grid rods and their design in the form ofstructural units will be apparent from the preferred examples.

In order to be able to vary the height of the shaft according toprevailing requirements and also to permit premanufacture provision ismade in accordance with an advantageous embodiment of the apparatus thatthe shaft is assembled from module members each forming a closed ring,including a grid and at least some of the module members comprise flowapertures, through the walls for the feeding and discharging of thegases.

In accordance with another modification of the shaft design the gridstake the form of structural units adapted to be introduced by slidingsideways through the shaft walls through closable window apertures. Thisdesign offers the advantage that the grids can be replaced relativelyeasily when they have become unservicable or if grids having differentgrid rod spacings are to be used to allow for different materials in theshaft.

By leaving free interspaces between adjoining beds, it is possible thatunderneath the respective stationary grid rods rebates are provided inthe shaft walls on the shaft inside for accommodating the operatingmeans for the movable grid rods respectively for the structural unitsformed thereby and drive means for the operating means are providedoutside of the shaft walls.

In order to counteract the formation of blockages of the gaps betweenthe grid rods due to the granulates it the grid rods, viewed in crosssection, in their upper portions can comprise a profile forming a waistregion and can be fitted with interchangable profile members. These haveadvantageously horse shoe-shaped projections in the longitudinaldirection of the grid rods serving as stop members for adjoining profilemembers. With these rider-shaped profile members, it is possible for agiven spacing of the grid rods to vary the relative proportion ofoverall free flow areas or to provide local variations thereof for anygiven grid. Moreover, by using rider-shaped profile members of differentcross sections, it is possible to influence even on a single grid themanner in which the trickle flow proceeds when the movable grid rods aretransferred into their open positions. Accordingly, it is possible bymeans of the rider-shaped profile members to influence the flow throughthe beds as well as the formation of the trickle flow with a view to theattainment of uniformity.

Because temperatures between 400° and 950° C. prevail in the shaft, itis necessary to use appropriate thermally resistant materials for theinternal structures in the shaft. It is advantageous for the grid rodsas well as the remaining load-bearing parts of the grid and thegrid-shaped inserts as well as the flaps held therein to be made ofceramic materials.

In order to attain the above described cooling of the lowermost bed inthe shaft in a particularly effective manner and simultaneously togenerate at least a portion of the steam required in the precedingtreatment zones, we can provide a spray device for feeding water aboveat least one of the beds of the cooling zone.

BRIEF DESCRIPTION OF THE DRAWING

The drawing illustrates diagrammatically an apparatus for carrying outthe process of the invention.

In the drawing:

FIG. 1 is a longitudinal section through a shaft for the manufacture ofactivated form coke as a granulate according to the invention,diagrammatically illustrating the gas flow;

FIG. 2 is a detail view on a larger scale of a portion of the sectionaccording to FIG. 1 at the level of a grid from which details of thegrid design are apparent,

FIG. 3, is a plan view of the embodiment according to FIG. 2;

FIG. 4 is a diagram of four possible positions of the grid rods whenarranged and designed in accordance with FIGS. 2 and 3;

FIG. 5 is a perspective view of two grid rods showing rider-shapedprofile members applied thereto;

FIG. 6 is a partial plan view of two parallel grid rods according toFIG. 4 with rider-shaped profile members applied thereto;

FIG. 7 is a partial longitudinal section through the shaft according toFIG. 1 in the region of a bed of the pyrolysis zone;

FIG. 8 is a reversed plan view against the flaps according to FIG. 7distributed over the shaft cross section;

FIG. 9 is an enlarged view of a cross section through one of the flapsaccording to FIGS. 6 and 7, and

FIG. 10 is a partial longitudinal section through a shaft havinglaterally insertable grids.

SPECIFIC DESCRIPTION

The shaft illustrated in FIG. 1 comprises a shaft wall, the whole ofwhich is denoted as 1 and is of square or rectangular cross section. Inthe shaft, grids 2 are fitted in the walls is spaced apart relation oneabove the other, such that between adjoining grids chambers 3 are formedwhich are only partially filled by planar beds 4 of granulate based onpretreated black coal to be treated in the shaft for the manufacture ofactivated form coke, such that between any two adjoining beds 4 a freeinterspace remains.

In the illustrated example the shaft is assembled from closed annularmodule members 5 fitted one above the other, each receiving therein agrid 2, such that the shaft can be manufactured from an appropriatenumber of module members 5 in varying heights and with accordinglyvariable numbers of levels.

At its lower end the shaft comprises a discharge aperture 9 closable bya slider 10, for discharging the activated coke granulates treated inthe shaft. Below the shaft a conveyor 10a for the onward conveyance ofthe granulates emerging from the shaft may be seen.

In an upward direction the shaft is closed by a closure casing designedin the form of an inlet lock 6. In a laterally projecting part of theclosure casing 6 a metering device 7, illustrated diagrammatically, isprovided in which the respective amount of pretreated granulates requirdfor a bed 4 is accommodated and from there is delivered to a slidablemold box 8, forming a flat bed having a uniform bed thickness over itscross section. This mould box is downwardly closed by a grid 2acorresponding to the grid 2 in the module members 5 of the shaft 1 andfitted with the same operating devices as are the grid 2 in the shaftand still to be described further below, so that after the transferenceof the mould box into the position above the free shaft cross section,the bed contained in the mould box 8 may be transferred onto the grid 2upwardly limiting the uppermost chamber 3a while maintaining a uniformbed thickness over the bed cross section.

The metering device 7 may comprise a grid corresponding to the grid 2 ofthe mould box and an additional means for levelling the surface of thebed to be accommodated. The interior of the shaft 1, including the bed 4contained therein can be subdivided into altogether five zones, moreparticularly from the top to the bottom into the zones I to V indicatedon the right hand side next to FIG. 1. The uppermost zone I constitutesthe pyrolysis zone. The zone II following thereon in the downwarddirection is the heating zone. The downwardly next following zone III isthe activating zone. This is followed by the post-treatment and thecooling zone represented by zones IV and V.

In the illustrated example the aforesaid zones I to V in the interior ofthe shafts 1 are each separated aerodynamically by partitions 11 eachformed by pivotal louver slats and adapted to be moved into the closedand open positions by movement of the slats. In FIG. 1 all slats are inthe closed position such that the partitions 11 are effective.

Between the uppermost bed in the shaft and the next bed further below, afurther similar partition 11a is provided which limits the pyrolysiszone I jointly with a closure bed provided undeneath the partition 11aand through which no flow passes, in respect of the particular bed newlyintroduced into the shaft, providing a closure in an aerodynamic sense.

Immediately underneath each of the grids of the pyrolysis zone I,grid-shaped inserts 12 can be seen combined with flaps 13 by which apartial flow through the beds contained on these grids in the pyrolysiszone I is made possible. Details of the grid-shaped inserts 12 and ofthe flaps 13 will be described in conjunction with FIGS. 7 to 9.

The grids provided in the shaft 1 of FIGS. 2 to 4 are each formed inpart by stationary grid rods 14 and in part by movable grid rods 15 and16. The latter are movable upwardly from the plane of the grid inrelation to the stationary grid rods 14 in order to temporarily increasethe free intervals between adjoining grid rods.

In FIG. 2 in the left hand part thereof, the position of the grid rods14 to 16 in the grid plane is shown, while in the right hand part thegrid rods 15 and 16 have been illustrated raised to different positionsin relation to the grid plane. For raising the grid rods 15 and 16,crank or pivot arms 18 are provided in nook-shaped rebates 17 inside theshaft wall and adapted to be pivoted from the outside by way of anoperating shaft 19. The movable grid rods 15 and 16 are longitudinallyextended in relation to the fixed grid rods 14 and are combined in eachcase in a raisable or lowerable structural unit, the extensions of thegrid rods 15 and 16 comprising crank arms 15a and 16a respectively ofdifferent lengths. The result is that, due to a pivoting movement of thecrank arms 18 about the pivoting axis 19, the grid rods 15 and 16 aremoved to different levels as can be see in the right hand half of FIG.2.

Instead of a raising of the movable grid rods 15 and 16 it is possibleas an alternative to provide for a lowering of such grid rods in such amanner that the grid rods 15 and 16 will adopt different relativepositions. In FIG. 4 four modifications of such different positions ofthe grid rods 14 to 16 in relation to one another are illustrated, ineach case the starting position of the grid rods being shown in brokenlines, while the possible end positions of the grid rods are shownshaded.

The grid rods illustrated diagrammatically in FIGS. 2 and 3, in practicehave a shape as illustrated in FIGS. 5 and 6. The grid rods may take theform of solid or hollow profile rods, the optional cavity in the case ofhollow profiles being illustrated in broken lines in the shaded sectionsurface of FIG. 5. The grid rods comprise a profile 20 having awaistline and are fitted with rider-shaped profile members 21. Theserider-shaped profile members 21 which can be mounted interchangeably onthe grid rods, each have a horse-shoe configuration and in thelongitudinal direction of the grid rods have projections 22 serving asstops against adjoining rider-shaped profile members. When theserider-shaped profile members 21 are densely packed on the grid rods,there results for the grid rods a pattern as illustrated in plan viewfor two adjoining grid rods in FIG. 6. FIG. 6 also shows that in thecase of adjoining grid rods the rider-shaped profile members 21 viewedin the longitudinal direction of the adjoining rods are preferablyprovided in staggered mutual relationship.

The rider-shaped profile members 21 have the effect that the lowermostlayer of granulates in any one bed is prevented from blocking the gapsbetween adjoining grid rods by the granulates being forced into mutuallystaggered positions, such that in the lowermost layer the intersticesthere remaining between the granulates permit a uniform impact andinflow of the treatment gases into the beds maintained on the grids. Therider-shaped profile members 21, for any given spacing of the grid rodsmay have different diameters such that the proportion of free crosssectional areas through the grids may be adjusted correspondingly or maybe varied overall or in places.

The arrangement and design of the grid rod shaped inserts 12 and of theflaps therein provided as used in the pyrolysis zone I are apparent fromFIGS. 7 to 9. Due to the grid-shaped insert 12, mutually parallel flowpassages 23 are formed over the entire cross sectional area of the grid2 or of the bed 4 in each of which one of the pivotal flaps 13 ismaintained. The flaps 13 are so held in the flow passages 23 in apattern like the squares of a chessboard that any adjoining flaps occupydifferent positions. In order to be able to jointly adjust the flaps 13of equal positions of any one row, two horizontal shafts 24, 25 arearranged one above the other in accordance with FIG. 9 on which theflaps 13 of any one row are mounted alternatingly. In a working exampleaccording to FIG. 9 the flaps 13 mounted on the shaft 25 accommodate ina rebate the shaft 24 of the respectively adjoining flaps without theseaxes 24 interfering with the pivoting movement of the flaps 13 held onthe axes 25. In this manner it is possible to move all flaps into theblocking position or all flaps into the open position or move theadjoining flaps into different positions.

Instead of the modular design of the shaft 1 described in conjunctionwith FIG. 1, the shaft wall may also be designed as a continuous walland comprise window apertures in accordance with the example of FIG. 10,through which the grids 2 are laterally insertable in the form of theabovementioned structural units.

In this context the grids 2 are held in groove-like rebates 27 of thelateral shaft walls by way of mounting means 28. For closing the windowapertures 26 in the shaft wall a filler member 25 of matchingconfiguration is provided in conjunction with a cover plate 30 whichafter the insertion of the filler member 29 can be screwed to the shaftwall. By the aforesaid design it is possible to replace at low cost andat short notice the grids 2 provided in the form of structural units.

In the following an example of the process according to the inventionwill be described with reference to FIG. 1. For that purpose a possiblepattern of process gas flow for the manufacture of activated cokegranulates in the illustrated shaft is illustrated diagrammatically andin a simplified fashion in FIG. 1. The various arrows represent thedirections of flow of the gases or vapors.

In the example all gas feed apertures 31 are provided in the right handwall of the shaft, while all discharge apertures 32 are provided in theleft hand wall of the shaft.

In accordance with the illustrated example, separate gas circuits areprovided for the zones I to IV but being of similar design. In theillustrated example a mixture of steam and CO₂ is used as the activatinggas. It is furthermore assumed that as the inert gas for the pyrolysiszone I and for the preheating zone II and also subsequently for thepost-treatment zone IV a mixture of steam and CO₂ serves as the inertgas.

In the individual circuits the blowers are each denoted as G, theburners in which the reaction gases respectively emerging from the shaftare subjected to post-combustion by B, the heat exchangers by W and themixing devices in which steam and CO₂ are mixed with the combustiongases by M. The feedlines for the air are denoted as L, the lines forfeeding the steam by D and the lines for freeing the CO₂ gas by C.

The drawing does not show the possible manner in which the heatexchangers W may be combined.

In the example it is assumed that the cooling of the beds prevailing inthe cooling zone V takes place exclusively by spraying of a bed by meansof a spray device 33 with water such that in the cooling zone, enteredby the beds at a temperature of about 800° C., steam is generated, aminor part of which is circulated whist the major part is passed throughthe duct D emerging from the cooling zone to the circuits I to IV, suchthat in the illustrated example the steam required for conducting theprocess is generated in cooling zone V. In the cooling zone the beds aresubjected to countercurrent flow. In the course thereof the beds arecooled to about 120° C. before the lowermost bed is transferred byopening the grid by means of the movable grid rods via the dischargeaperture 9 and, with the slider 10 opened, onto the further conveyor10a. After returning the grid rods of the lowermost grid into the closedposition, the grids following in an upward direction are openedsuccessively level by level and the partitions 11 and 11a respectivelyare moved to the open positions of the louver slats. The flaps 13 aswell in the grid-shaped inserts 12 are all moved to the open positionsuch that the beds may successively pass unhibitedly in the form of atrickle flow onto the next following grid where they once again for abed of uniform bed thickness right across. Once the fowarding of the bedonto the next following grid has been completed, the partitions 11 and11a are returned to their closed positions by pivoting the flaps and theflaps 13 in the grid-shaped inserts 12 are moved to the respectiveposition desired for the particular stage of the process in thepyrolysis zone, depending on whether a partial movement of thegranulates in the beds prevailing in that zone is desired or not.

The uppermost grid which has been rendered empty by the movement of thebed is charged once again by the feeding of the contents of the mold box8 which in the meantime has been filled with a bed from the meteringdevice 7, the feeding of the bed from the mold box 8 proceeding in thesame manner as described in the context of the remaining grids 2 in theshaft 1.

In the pyrolysis zone two beds are subjected successively incountercurrent to a flow of pyrolysis gas therethrough in theillustrated example. In this case the pyrolysis gases have a temperatureof about 400° C. In order to reliably prevent any passage of thepyrolysis gases in an upward direction, a bed is provided below thepartition 11a through which no pyrolysis gases flow and which serves asa blocking bed.

The beds in the pyrolysis zone are subjected to a flow therethrough fora duration of two residence periods and hence pass into the heating zoneII in which in accordance with the example they are once again subjectedto a flow therethrough for two residence periods. However, in that casethe flow therethrough on the two grids there provided proceeds inopposite directions. In the heating zone the beds are subjected to aflow therethrough of an inert gas composed of steam and CO₂ at atemperature of 900° C.

In the subsequent activation zone four grids are provided in the examplesuch that the beds are there subjected to a flow therethrough ofactivating gas during four periods of residence, once again inalternating directions from one stage to the next. In this case theactivating gas feed has a temperature of about 950° C. The reaction gasemerging from the activating zone which due to the chemical reaction isproduced in a larger volume than that of the activating gas feed, may asan alternative to what is illustrated in FIG. 1 be passed into thecircuit of the heating zone in order to at least partly provide the gassupply required there.

The subsequent post-treatment zone IV once again provides that the bedsare post-treated at four levels, i.e. spending four periods of residencein that zone, the beds from one level to the next being subjected toflows therethrough in opposite directions, more particularly by apost-treatment gas at a temperature of about 800° C.

Cooling of the beds follows at two levels by means of injected water asdescribed further above. In this context provision is made for the spraydevice 33 to be provided above the lowermost bed in the cooling zone,such that the steam generated in that zone is heated by being passed incountercurrent through the bed which is uppermost in the cooling zoneprior to its being discharged by way of the duct D into the abovedescribed preceding zones.

The black coal to be used for the manufacture of the granulates to beactivated in the shaft can be pretreated in a known manner by extractionor oxidation. Its treatment after the activation in the post-treatmentzone is possible with widely different gases or gas compositions andalso at widely varying temperatures depending on the subsequentlyintended use of the activated coke particles.

In all stages of the shaft according to FIG. 1 an intensive flow of gaspasses through the beds, more particularly in each case in a directionnormal to the plane of the bed, the feeding and discharge of the gasesthrough the free interspaces provided between the beds assuring auniform feeding to and from the beds over their cross sections. Abrasionof the granulates during the treatment in the above described manner isexceptionally low, because the granulates are not subjected to majorstatic pressure and need not move while under such pressure as is thecase with continuous beds or material columns.

Due to the intensive flow through the beds of the individual gases andas a result of the intensive and uniform exposure to flow of allindividual granulates of the beds, there result exceptionally lowreaction periods and correspondingly low residence periods. In thiscontext the gas compositions, their temperatures and also the flowvelocities in the individual zones can be varied within wide limits andbe adapted to the particular requirements for attaining a particularlyhigh effectivity.

From the aforegoing it will be apparent that by judiciously andskilfully applying the teachings of the present invention it is possibleto provide a process of the type described in the introduction in whichthe stated drawbacks are avoided or mitigated and in which allgranulates are subjected to uniform effects and flow exposure combinedwith a favourable aerodynamic effectiveness, i.e. a favorable ratio oftransferred output to applied mechanical input.

We claim:
 1. A method of making active form coke from coal, comprisingthe steps of:(a) granulating coal particles with a binder to form agranulate comprising granules of a particle size of substantially 6 to25 mm; (b) passing said granulate downwardly through a reactor shafthaving a plurality of vertically spaced bar grates therein formed with aplurality of bars lying in respective horizontal grate planes by:(b₁)depositing said granules in layers of uniform thickness on said bargrates over substantially the entire cross section of the shaft so thatsaid layers form respective beds and above each layer a free space isprovided, and (b₂) displacing, after a respective treatment time for thegranules on each grate, at least a portion of the bars of eachrespective grate out of the respective grate plane to permit thegranules on the respective grate to trickle uniformly through anunderlying one of said free spaces onto a next-lower-lying grate andreform a layer of uniform thickness thereon over substantially theentire cross section of the shaft beginning from a lower grate and thensucceedingly higher grates, thereby causing said granulate to pass insuccession through a preheating and pyrolysis zone, a heating zone andaftertreatment zone and a cooling zone of said shaft and effectingpyrolysis of the granules to transform them into active form coke, eachof said zones having at least one of said grates; (c) in each of saidpreheating, heating and aftertreatment zones passing a gas selected fromthe group which consists of CO₂ and steam through the respective bedgenerally perpendicular to the respective grate plane by laterallyintroducing the gas into said shaft in a free space on one side of therespective bed and laterally withdrawing the gas from a free space on anopposite side of the respective bed after it has traversed the said bed;(d) spraying water on said granules on at least one of said grates insaid cooling zone; and (e) partially shielding at least one of said bedsin at least one of said zones against passage of said gas therethroughuntil a granule-loosening threshold has been reached in a portion of thepartially shielded bed through which the gas continues to pass andthereafter permitting the gas to pass through the previously shieldedportion of the bed.
 2. The method defined in claim 1 wherein said gas ispassed through at least one of said beds formed on at least one of saidgrates in said pyrolysis zone upwardly in counterflow to the directionin which said granules pass through said reactor shaft.
 3. The methoddefined in claim 1 wherein the gas is passed upwardly through the bedwhich is partially shielded and the partially shielded bed lies in thepyrolysis zone.
 4. The method defined in claim 1 wherein the heating andaftertreatment zones include a plurality of bar grates having bedsformed thereon and the gas is passed upwardly through some of said bedsin said heating and aftertreatment zones and downwardly through othersof said beds in said heating and aftertreatment zones.
 5. The methoddefined in claim 1 wherein steam is generated in step (d) by sprayingwater on said granules in said cooling zone and the steam thus producedis then passed through a respective bed in at least one other of saidzones.
 6. The method defined in claim 1, further comprising the step ofdistributing gas flow during step (c) through at least one of said bedsby selectively opening and closing flaps underlying said at least one ofsaid beds after trickling therefrom in step (b) has ceased.
 7. A methodof making active form coke from coal, comprising the steps of:(a)granulating coal particles with a binder to form a granulate comprisinggranules of a particle size of substantially 6 to 25 mm; (b) passingsaid granulate downwardly through a reactor shaft having a plurality ofvertically spaced bar grates therein formed with a plurality of barslying in respective horizontal grate planes by:(b₁) depositing saidgranules in layers of uniform thickness on said bar grates oversubstantially the entire cross section of the shaft so that said layersform respective beds and above each layer a free space is provided, and(b₂) displacing, after a respective treatment time for the granules oneach grate, at least a portion of the bars of each respective grate outof the respective grate plane to permit the granules on the respectivegrate to trickle uniformly through an underlying one of said free spacesonto a next-lower-lying grate and reform a layer of uniform thicknessthereon over substantially the entire cross section of the shaftbeginning from a lower grate and then succeedingly higher grates,thereby causing said granulate to pass in succession through apreheating and pyrolysis zone, a heating zone and aftertreatment zoneand a cooling zone of said shaft and effecting pyrolysis of the granulesto transform them into active form coke, each of said zones having atleast one of said grates; (c) in each of said preheating, heating andaftertreatment zones passing a gas selected from the group whichconsists of CO₂ and steam through the respective bed generallyperpendicular to the respective grate plane by laterally introducing thegas into said shaft in a free space on one side of the respective bedand laterally withdrawing the gas from a free space on an opposite sideof the respective bed after it has traversed the said bed; and (d)spraying water on said granules on at least one of said grates in saidcooling zone, said portion of the bar of each grate being displaced outof the respective grate plane by lifting them above others of the barsof the respective grate which remain in said grate plane.
 8. The methoddefined in claim 7 wherein said gas is passed through at least one ofsaid beds (on at least one of said grates) in said pyrolysis zoneupwardly in counterflow to the direction in which said granules passthrough said reactor shaft.
 9. The method defined in claim 7 wherein theheating and aftertreatment zones include a plurality of bar grateshaving beds formed thereon and the gas is passed upwardly through someof said beds in said heating and aftertreatment zones and downwardlythrough others of said beds in said heating and aftertreatment zones.10. The method defined in claim 7 wherein steam is generated in step (d)by spraying water on said granules in said cooling zone and the steamthus produced is then passed through a respective bed in at least oneother of said zones.
 11. The method defined in claim 7, furthercomprising the step of distributing gas flow during step (c) through atleast one of said beds by selectively opening and closing flapsunderlying said at least one of said beds after trickling therefrom instep (b) has ceased.